The present disclosure relates to a transmission device, a transmission method, a reception device, a reception method, a communication system, and a communication method.
In recent years, there have been cases where, in digital signage and an advertisement, a bar code such as a QR code (registered trademark) is embedded into information shown to a user for attracting the user's attention to a website and the like. The bar code is embedded into the information in a form that a bit pattern obtained by encoding letters and numbers can be seen by the human eye. Accordingly, for example, when a position at which it is visually recognized by the user that the bit pattern is embedded is imaged by a camera provided to a mobile phone, and an image obtained as a result of the imaging is analyzed by the mobile phone, the bit pattern may be converted into a URL (Uniform Resource Locator) for specifying a website, a telephone number, and the like.
According to such a technique, the user can, even if the user does not have a special bar code reader, use the camera for the imaging purpose provided to the mobile phone as the bar code reader. With such an advantage, a bar code imaged by a camera is in widespread use. However, since the bar code is used by being embedded into information in a form that can be identified by the human eye, when the bar code has a size of a certain level or more, the beauty of the advertisement and the like that is the information into which the bar code is embedded is spoiled. On the other hand, unless the bar code has a size of a certain level or more, it becomes difficult for the user to recognize a position at which the bar code is embedded and to grasp the position to be imaged.
Further, a technique called visible light communication in which data is transmitted using visible light that is viewable by the human eye is drawing attention (for example, see JP2009-290359A). The influence of the visible light communication on the human body is less than the influence of communication using radio waves or infrared rays on the human body, and, in addition, the visible light communication has a feature that a position capable of receiving data can be confirmed with the human eye.
As a device for emitting the visible light in the visible light communication, there is used an LED (Light Emitting Diode), for example. This is mainly because, since the LED is a semiconductor device, the LED is capable of modulating the light emitted from the LED at such high speed that it is difficult for a human to identify the light, and is capable of transmitting data at high speed as an optical signal. Therefore, for example, when the light emitted from the LED is used as the light used for an illumination, a display, and the like, the possibility can be reduced that the beauty of the advertisement and the like is spoiled, and, also, the illumination and the display can be used as a transmission device for transmitting data.